I am unable to play Overwatch as when I try to start up the game it comes up with Account Missing Overwatch license. I know that I have one as I have just added the key to my account nov 26.th
If you have another battle.net account then you may wish to login to that one to make sure you did not add the key to the wrong account.
If you still have the key then you could try to claim it again on this account and see what happens.
If it turns out you have added it to the wrong account or still have issues you will need to reach out to the support team - https://eu.battle.net/support/en/
I have tried that and now it sais the key has already been used, it didn’t do that the first time, and it said it was overwatch that i added, i have googled it and found some1 who had a similar issue, please look at https://us.forums.blizzard.com/en/overwatch/t/missing-overwatch-license/158077